Method for forming filter cigarettes



United States Patent 2,996,065 METHOD FOR FORMING FILTER CIGARETTESOhver S. North, 2119 4th St. NW., Washington 7, D.C. No Drawing. FiledSept. 9, 1958, Ser. No. 759,851 2 Claims. (Cl. 131-10) This inventionrelates to smoking tobacco compositions for cigarettes, and moreparticularly to tobacco having associated therewith a quantity of acertain additive, which mixture When formed into a cigarette and smokedWlll produce a filtered smoke. Specifically, it relates to a method ofincorporating that additive in the tobacco in such a way that optimumfiltration and smoking properties will be realized in cigarettes formedfrom that com- P08111011.

The present application is a continuation-in-part of my earlierapplication, Serial No. 665,120, filed June 12, 1957, which issued onOctober 4, 1960 as United States Patent 2,955,060, wherein there aredisclosed tobacco mixtures in which randomly oriented particles of theadditive are uniformly distributed throughout the tobacco mixture.

' A number of compositions for and methods of filtering nicotine, dust,and impurities from tobacco smoke before it is drawn into the smokersmouth are known. Many of these are comparatively expensive andinconvenient to manufacture and/ or use, and it is desirable to producea product having self-contained and inexpensive, yet relativelyeffective, means for accomplishing filtration of smoke.

The principal object of this invention is to provide a method for makingtobacco compositions and cigarettes which when smoked will have thesmoke filtered of a large portion of its content of nicotine and othertars, dust, and

impurities.

Another object is to provide cigarette tobacco compositions andcigarettes that can be manufactured at a cost lower than or closelycomparable with the cost of like standard articles of commerce.

Another object is to provide a method of manufacturing filter cigarettesof the size, shape, and general appearance of standard commercialproducts.

The objects of this invention are accomplished by disseminatingquantities of unexpanded, or unexfoliated, vermiculite in the tobacco insuch manner that in cigarettes manufactured from the composition thevermiculite particles are orientated in a particular direction, asdescribed later.

I have discovered that when a cigarette consisting essentially of anadmixture of tobacco and a limited quantity of unexfoliated vermiculitedisposed substantially uniformly throughout the portion of the cigarettewhich is to be smoked (hereinafter designated as the body of thecigarette) is ignited and smoked in the usual way, the containedvermiculite particles nearest the spark will be exfoliated, due to thefact that the burning tobacco particles produce sufiicient heat to causethe vermiculite particles to undergo the phenomenon of exfoliating, thatis, the laminae of each particle being caused to separate in somedegree, although the individual particles retain coherent, unit form.

I have further discovered that if the unexfoliated vermiculite particlesare incorporated uniformly in the tobacco throughout the body of thecigarette with their crystallographic axes in correct alignment withrespect to the longitudinal axis of the cigarette, said cigarette can bereadily smoked and the resulting smoke will be filtered of anappreciable portion of its content of tars, dust, etc., which mightotherwise be drawn into the smokers mouth. When a cigarette soconstituted is smoked there is sufficient expansion of vermiculiteparticles located at the point of spark to provide a plurality of thinplatelets through which the smoke will be drawn to accomplish desirablefiltration and prevent some of the nicotine and impurities from beingdrawn into or through the remaining body of the cigarette, yet at thesame time there is insulficient volume increase to split the wrapperpaper or otherwise to disrupt the cigarette. As burning of the cigaretteprogresses, successive portions of vermiculite are thus expanded and arediscarded along with the tobacco ash. This type of filtration ispreferable to that accomplished by filter sections, or filter tips,"because a filter section or tip, of whatever composition or type, tendsto become progressively more clogged with accumulating tars, nicotine,etc., as smoking proceeds, thus losing some of its effectiveness.Furthermore, it is generally somewhat more economical to manufacture acigarette composed wholly of a physical intermixture of materials thanone requiring provision of a special section or tip which initially isseparate from the main body of the cigarette.

A corollary benefit derived from the exfoliation phenomenon under theconditions just described stems from the fact that the unexpandedvermiculite acts as a thermodynamic heat sink. As the unexpandedvermiculite is exposed to the heat of the burning tobacco, heat isnecessarily used to accomplish the exfoliation, and water ofcrystallization is released. The presence, of water vapor right in thecombustion area, which enhances the condensation of the products ofcombustion, and the lower smoke temperature are important factorscontributing to the desirability of having unexpanded vermiculitedistributed throughout the tobacco as described.

It may be here pointed out that a ton of unexpanded vermiculite, whichcan be bought for a few dollars, will make many tens of thousands ofcigarettes, and therefore this material is most economical to use forthis purpose. The cost per unit of filter cigarettes manufactured inaccordance with this invention is less than, or closely comparable with,the cost per unit of cigarettes made without vermiculite.

Vermiculite is a micaceous, hydrated magnesium-aluminum silicate mineralwhich is well known in industry, particularly in the construction,chemical, and agricultural fields. While vermiculite is of fairlywidespread mineralogical occurrence, the bulk of the commercial materialnow comes from the States of Montana and South Carolina in the UnitedStates and from the Transvaal, Union of South Africa. As prepared forthe market, ores containing vermiculite are mined and then beneficiated,or purified, by various methods of concentration and sizing, so that thefinal product consists almost entirely of unexpanded vermiculitecrystals of more or less uniform thickness and equal lateral dimensions.Expansion, or exfoliation, of vermiculite can be accomplished atrelatively very low temperatures, for example by a match flame, ascontrasted with most other expandable inorganic materials which requiremuch higher heats. Expansion of vermiculite is due to separation andwarping of the individual laminae. The final particle possesses a verylarge surface area and consists of a succession of extremely thinplatelets loosely attached to adjacent platelets and separated from oneanother by more or less flat air spaces.

Vermiculite is inorganic, and during the expansion process contemplatedin this invention is free of violent efiects, disagreeable odors ortastes, or any other form of objectionable manifestation.

In the manufacture of cigarettes in accordance with this method, I firstform an intermixture of quantities of tobacco and unexfoliatedvermiculite particles, the latter being aligned as hereinafterdescribed. I prefer to use 3 smoking tobacco of any of various suitabletypes commonly used in the manufacture of cigarettes. The tobacco usedmay contain additives, such as for binding or flavoring or otherwiseimproving the qualities of the finished product, or such additives maybe added during or after the mixing of the tobacco and unexfoliatedvermiculite. The vermiculite used may be of a particle size gradeavailable on the market; alternatively, a grade which is commerciallyavailable may be sized to produce a fraction meeting specialspecifications.

A large proportion, for example 95 to 99 percent, by weight, of thedesired cigarette tobacco is intermixed with a small amount, for example1 to 5 percent, by weight, of the proper grade of unexfoliatedvermiculite. Generally, it will be preferable to use one of theintermediate particle size grades of vermiculite, for example a grade ofwhich about 95 percent will pass a 28-mesh Tyler screen and the bulk ofwhich will be retained on a 50mesh Tyler screen, or it may be desired touse a more closely sized material, for instance one in which most of theparticles will pass a 28-mesh Tyler screen but will be retained on a35-mesh Tyler screen. It will be understood that these proportions arecited merely as examples, and that I do not limit the scope of thisinvention as regards the proportions of the materials and the particlesize grades of the vermiculite used.

A critical factor in the manufacture of cigarettes in accordance withthis invention is the alignment of the vermiculite particles in thetobacco, and subsequent formation of cigarettes with due regard for saidalignment. vermiculite flakes are impervious to air and smoke in thedirection of the thin dimension, that is, in the direction at rightangles to the crystallographic basal cleavage plane of vermiculite. Ifthe vermiculite particles are situated in random positions through thetobacco, many of the particles will be caused to expand at suchattitudes as to tend to block the flow of air and smoke through the bodyof the cigarette to the mouth of the smoker, thereby rendering itdiflicult or impossible to draw on the cigarette satisfactorily.Therefore, controlled dissemination of the vermiculite in the tobacco isdesirable and necessary, not only with regard to uniform distribution ofvermiculite particles through the tobacco, but also to make certain thatsubstantially all of the vermiculite flakes are so aligned that thecrystallographic basal cleavage plane of every vermiculite crystal isorientated in the approximately same direction, so that it may beassured that these basal cleavage planes will lie substantially parallelwith the longitudinal axis of cigarettes thereafter formed from thesubject composition. Such aignment may be produced, for example anddepending on the structural details of the cigarette machine used, byfeeding a thin stream of vermiculite over a metal strip positionedimmediately above and longitudinally of the tobacco belt in thecigarette machine, in such manner as to drop vermiculite flakes onto thebelt simultaneously with the feeding of tobacco thereto.

The composition of tobacco and aligned unexpanded vermiculite particlesis fed onto the cigarette paper in such a way, for example over the endof the tobacco belt mentioned above, that the basal cleavage planes ofthe bulk of the particles are aligned more or less parallel with thelongitudinal axes of the cigarettes. The composition may be formed intocigarettes by any appropriate procedure and using any suitable machineor apparatus. Cigarettes so formed may be of any desired length,crosssection shape, etc., but it Will generally be preferable that suchproducts be of standard lengths and shapes.

The composition may be used in the manufacture of cigarettes containingno other provision for smoke filtration; or, combustible body sectionsconsisting of quantities of this composition properly wrapped and sealedin paper may be attached to filter tips, for example of celluloseacetate, to produce cigarettes possessing maximum filtrationcharacteristics. In the latter instance it may be found advantageous touse comparatively small-sized vermiculite particles and/or a relativelylimited proportion of vermiculite in the composition, so as toaccomplish only a part of the desired filtration near the point ofspark.

I claim:

1. In a smoking mixture formed by intimately admixing flakes ofunexpanded vermiculite With tobacco to obtain a mixture of from l5%vermiculite in from to 99% of tobacco, the improvement which comprises:depositing the flakes of unexpanded vermiculite and tobacco onto asupport with substantially all of the flakes of unexpanded vermiculitealigned in a common orientation and thereafter forming the mixture intoa smoking tobacco product wherein the basal cleavage planes in theunexpanded vermiculite and the direction of draw of the smoking productare parallel to one another.

2. A smoking product formed with from 15% of flakes of unexpandedvermiculite and 95-99% of tobacco, intimately mixed and combined withinan outer wrapper and wherein the basal cleavage planes in the flakes ofunexpanded vermiculite are parallel to the direction of draw of thesmoking product.

References Cited in the file of this patent UNITED STATES PATENTSGraybeal Mar. 21, 1957 OTHER REFERENCES

1. IN A SMOKING MIXTURE FORMED BY INTIMATELY ADMIXING FLAKES OFUNEXPANDED VERMICULITE WITH TOBACCO TO OBTAIN A MIXTURE OF FROM 1-5%VERMICULITE IN FROM 95 TO 99% OF TOBACCO, THE IMPROVEMENT WHICHCOMPRISES: DEPOSITING THE FLAKES OF UNEXPANDED VERMICULITE AND TOBACCOONTO A SUPPORT WITH SUBSTANTIALLY ALL OF THE FLAKES OF UNEXPANDEDVERMICULITE ALIGNED IN A COMMON ORIENTATION AND THEREAFTER FORMING THEMIXTURE INTO A SMOKING TOBACCO PRODUCT WHEREIN THE BASAL CLEAVAGE PLANESIN THE UNEXPANDED VERMICULITE AND THE DIRECTION OF DRAW OF THE SMOKINGPRODUCT ARE PARALLEL TO ONE ANOTHER.